Free float

Also called: Free-float market capitalisation · Topic: Financial Markets, Instruments, Insurance and Pensions · NCERT: Beyond NCERT

Meaning

Free float is the part of a company's shares that is actually available for trading in the market. It leaves out shares held by promoters (the founders or controlling group of the company) and shares that are locked in (not allowed to be sold for a fixed period).

It matters because the Sensex and the Nifty 50 weight each company by its free-float market capitalisation, not by its total value. So a company counts in the index only as much as its tradable shares justify.

• Market capitalisation = share price × number of shares outstanding
• Free-float market capitalisation = free-float share (%) × market capitalisation

Explanation

How it works

• A company's shares are held by two broad groups:
• Promoters, plus holders of locked-in shares. These shares are held for control. They rarely come to the market.

• Everyone else, such as retail investors, mutual funds and foreign investors. These shares change hands every day in the secondary market (the market where investors buy and sell existing shares among themselves).

• Only the second group is the free float.

• Free-float market cap is the market value of this tradable part alone.

Worked example

• Step 1: total market cap. Share price ₹500 × 10 crore shares = ₹5,000 crore.
• Step 2: free float. Promoters hold 60%. So the free float is 100% − 60% = 40%.
• Step 3: free-float market cap. 0.40 × ₹5,000 crore = ₹2,000 crore.
• What this means for the index: the company enters the index calculation at ₹2,000 crore, not ₹5,000 crore.

Why indices use free float

• The problem: some companies have a very large promoter holding. With full market cap, such a company could move the index a lot, even though few of its shares are actually traded.
• The fix: free-float weighting means each company moves the index only in line with the shares investors can actually buy and sell.
• The result: the index gives a truer picture of the market that investors really face.

How a free-float index is calculated

• Index = (current free-float market cap of the index stocks ÷ base-period free-float market cap) × base value
• Worked example: suppose the base-period market cap was ₹1,000 crore and the base value is 100. Today's free-float market cap is ₹8,00,000 crore.
• Index = (8,00,000 ÷ 1,000) × 100 = 80,000.

What makes free float rise or fall

• It rises when:
• promoters sell part of their stake to the public

• a lock-in period ends, so those shares become free to trade

• It falls when:

• promoters buy more shares
• new shares are issued to promoters with a lock-in

In India

• Sensex (BSE):
• BSE was set up in 1875. It is Asia's oldest stock exchange.
• The Sensex tracks 30 large, actively traded companies.
• Base year: 1978-79 = 100.

• It has been weighted by free-float market capitalisation since 2003.

• Nifty 50 (NSE):

• It tracks 50 large, liquid companies. Liquid means the shares are easy to buy and sell without moving the price much.
• Base: 3 November 1995 = 1000.

• It is also weighted by free-float market capitalisation.

• Where the shares are held: free-float shares are held and traded in demat accounts (accounts that hold shares electronically instead of as paper certificates). These accounts are kept through the two depositories:

• NSDL (1996)
• CDSL (1999)

• Both work under the Depositories Act, 1996.

• Growth of the investor base: demat accounts crossed 21.6 crore in FY26 (till December 2025) [4]. More retail investors now hold and trade the free-float part of Indian companies.

• Circuit breakers: the market-wide circuit breaker (an automatic halt in trading when prices move too far) works on moves of 10%, 15% or 20% in the Sensex or the Nifty 50 [1][2]. Both of these are free-float indices.

Don't confuse with

• Full market capitalisation: this is price × all shares outstanding, including promoter shares. Free-float market cap counts only the tradable shares. In the example above, full market cap is ₹5,000 crore and free-float market cap is ₹2,000 crore.
• SEBI's size bands (large-, mid- and small-cap): these rank companies by market capitalisation. Large-cap = top 100, mid-cap = 101 to 250, small-cap = 251 onwards. This is a ranking system for classifying companies. It is different from free-float weighting, which decides how much each stock counts inside an index.
• Market capitalisation-to-GDP ratio (the "Buffett indicator"): this uses the total market cap of all listed companies ÷ GDP × 100. It measures whether the market as a whole may be over-valued. Free float measures how much of one company's stock can be traded.
• Liquidity: free float is the quantity of shares available to trade. Liquidity is how easily they are actually traded. A stock can have a large free float but still be thinly traded.

Prelims Hooks

• Free float = all shares minus promoter holdings and locked-in shares. Free-float market cap = free-float % × (price × shares outstanding).
• Sensex: 30 stocks, base 1978-79 = 100, free-float weighted since 2003.
• Nifty 50: 50 stocks, base 3 November 1995 = 1000, also free-float weighted.
• Index formula: (current free-float market cap ÷ base-period free-float market cap) × base value.
• Trap: a company with the biggest total market cap need not have the biggest weight in the Sensex or Nifty. A large promoter holding lowers its free-float weight.
• Trap: buying and selling free-float shares in the secondary market does not raise fresh capital for the company. The money only moves from one investor to another.

Mains Points

• Fairer indices and better price discovery:
• Free-float weighting stops promoter-heavy companies from swinging the Sensex or Nifty more than their tradable shares justify.
• When few shares are free to trade, a small amount of money can push the price up or down sharply. That makes such a stock easier to rig.

• The Harshad Mehta scam (1992) and the Ketan Parekh scam (2001) showed how chosen stocks could be pushed up artificially. A wider free float makes that harder.

• Promoter control versus market depth:

• A high promoter stake gives stable control of the company.
• But it shrinks the free float. Price discovery then becomes weaker, and the company gets a smaller weight in the index.

• A larger free float lets more investors take part, as demat accounts cross 21.6 crore (FY26) [4]. It also deepens the capital market.

• Reading valuation signals carefully:

• Headline measures such as the BSE market cap-to-GDP ratio of 136% at the end of December 2024 [3] use total market cap.
• Indices track only free-float value.
• A good answer should say which measure is being used before judging whether the market is over-valued.

Related concepts

• Secondary market
• Depository
• Demat account
• Clearing corporation
• T+1 settlement
• Algorithmic trading
• Circuit breaker
• Sensex
• Nifty 50
• Market capitalisation

Read more

• Secondary market: trading infrastructure, indices and valuation